Dermot Mulroney dates Zooey Deschanel on New Girl tonight!

Fancyman Russell and Jess return for part 2

Have you fallen in love with Dermot Mulroney on New Girl yet? The divorced doctor is trying to woo Jess, but he's also been captured by the rest of the cast as well.

Fox's New Girl isn't funny solely because of its script. Most of the hilarity roots from improvised moments -- something that kept veteran actor Dermot Mulroney on his toes as a guest on the show.

"The way they throw the material at them on the fly is fascinating," Mulroney told The Hollywood Reporter. "Sometimes you are saying lines on camera that you've never even heard or seen written down before. They are just shouting them at you. It's kind of like a peanut gallery… like some kind of controlled improv or rolling ad-lib within the script itself. It's a really interesting process, and they are all really good at it. I'd never done that type of shooting before, it was great fun."

"It’s like they are heckling you while you are trying to act," he explained. "It's time-consuming, of course, but it’s smart… The whole cast and crew work long hours to get the best on television they can, which I really admire. There is no slouching on this show."

Initially, Mulroney only signed on for three episodes, but his arc has been extended to cross paths with Jeanne Tripplehorn. The Big Love actress will play Russell's ex-wife who accidentally spends a lot of time with Jess.

"They have more scenes together than I do," says Mulroney, "but we do have a scene with [Tripplehorn] at a restaurant, so you can really look forward to that one."